Abstract
Iron-based oxygen carriers supported on alumina or alumina/titania were prepared and evaluated for chemical looping combustion of methane. The reduction conversion of Fe(2)O(3)/Al(2)O(3) and Fe(2)O(3)/Al(2)O(3)/TiO(2) particles was markedly increased with increasing inlet concentration and was slightly enhanced by elevated operating temperatures. According to the shrinking core model, the mass transfer coefficients (k (g)) of Fe(2)O(3)/Al(2)O(3) and Fe(2)O(3)/Al(2)O(3)/TiO(2) reduction with methane are found to be 0.07 and 0.12 mm s(-1). Complete combustion of methane is almost achieved for experiments conducted with Fe(2)O(3)/Al(2)O(3) and Fe(2)O(3)/Al(2)O(3)/TiO(2) operated as the Fe(2)O(3)/CH(4) molar ratio reached about 5.4 and 4.4, respectively. Carbon deposition during methane combustion was avoided by using Fe(2)O(3)/Al(2)O(3)/TiO(2) as an oxygen carrier. More heat was generated for the combustion of methane by Fe(2)O(3)/Al(2)O(3)/TiO(2) oxygen carriers because methane more fully reacted with the Fe(2)O(3) contained in the Fe(2)O(3)/Al(2)O(3)/TiO(2) oxygen carriers.